The purpose of this project is to conduct research in statistical methods with particular emphasis on those appropriate to the analysis of data from clinical and diagnostic trials and epidemiological studies of cancer. Many of the problems studied under this project arise from the consultative activities of the Section. In the past year this research has included a study of methods of comparing multiple treatment groups with unequal censoring patterns, development of a method for comparing different staging systems, a new test for exponentiality, development of survival models incorporating covariate information based on the Meibull distribution, the study of methods for choosing the best of several complex survival models for fitting the observed data, an investigation of the effects of stratification in randomized clinical trials, a study of how thresholds should be determined for diagnostic tests, and work was continued on the problem of determining the optimal treatment for patients based on initial covariate information. BIBLIOGRAPHIC REFERENCES: Byar, D. P., Simon, R. M., Friedewald, W. T., Schlesselman, J.J., DeMets, D.L., Ellenberg, J. H., Gail, M. H. and Ware, J. H.: Randomized clinical trials. New England Journal of Medicine 295: 74-80, 1976. Gail, M. H.: Letters: Mass vaccination: Probability of three sudden deaths. Science 195: 934-936, 1977.